a) Field of the Invention
The invention relates to a steering column for a motor vehicle with a bracket unit bearing a steering spindle, which unit is secured in position on a vehicle-stationary part. The securement bolts penetrate through elongated holes in the bracket unit or in the vehicle-stationary part, and the bracket unit in the event of a crash, starting from a starting position, is displaceable in the elongated holes with respect to the vehicle-stationary part with the displacement of the securement bolts.
b) Description of Related Prior Art
Steering columns in which a bracket unit bearing the steering spindle is connected with a vehicle-stationary part, such that in the event of a crash a displacement of the bracket unit relative to the vehicle-stationary part is made possible, are known in various implementations. DE 10 2006 020 650 B3, for example discloses a steering column in which the bracket unit is implemented as a carriage guided by a vehicle-stationary mounting unit. The bracket unit includes grooves extending bilaterally to the steering spindle in the longitudinal direction, into which grooves extend projections of the mounting unit directed toward one another. For the energy absorption during the displacement of the bracket unit with respect to the mounting unit in the event of a crash, energy consuming means acting between the bracket unit and the shell unit are additionally provided.
EP 0479 455 A2 discloses a steering column in which a bracket unit bearing the steering spindle is connected with a vehicle-stationary part using securement bolts. The securement bolts penetrate elongated holes formed in the bracket unit, whereby displacement of the bracket unit with respect to the vehicle-stationary part is made possible in the event of a crash. Each of the elongated holes has herein an enlarged section which, in the starting position of the bracket unit, is penetrated by the securement bolt. In the remaining region the width of the elongated hole is smaller than the diameter of the securement bolt, whereby the energy absorption is attained during the displacement of the bracket unit in the event of a crash. Further steering columns in which load bearing bolts penetrate through elongated holes in a bracket unit and are displaced in them in the event of a crash are disclosed in U.S. Pat. No. 3,769,851 and U.S. Pat. No. 6,378,903 B1. Through the cooperation of the securement bolt with implementations of the elongated hole hindering its displacement in the elongated hole, an energy absorption takes place in each case. One disadvantage of these steering columns is the constructional length required for the implementation of the elongated holes.
Also known is that the securement of the bracket unit on a vehicle-stationary part by means of securement bolts takes place through holes or cutouts of the bracket unit, which are open toward the steering-wheel side margin of the steering column. In the event of a crash, the bracket unit can become detached from the vehicle-stationary part with the disadvantageous result that the driver-side section of the steering column falls onto the legs of the driver. This is especially disadvantageous in the case of steering columns with steering force boosting means integrated into the steering columns, which have a greater weight.
U.S. Pat. No. 6,523,432 B1 discloses a steering column in which the bracket unit is detachable from the vehicle-stationary part in the event of a crash. The shell tube rotatably supporting the steering spindle is provided at its steering-wheel remote end with a metal retaining sheet including an elongated hole through which a bolt penetrates for the displaceable securement of the shell tube on a vehicle-stationary part.